GALCIT Colloquium
Guggenheim 133 (Lees-Kubota Lecture Hall)
Simulating Flow Over Roughness: Myths and Opportunities
Daniel Chung,
Lecturer ,
Mechanical Engineering,
University of Melbourne ,
I will present some historical overview of roughness research and then
describe a fast direct numerical simulation (DNS) method that promises
to directly characterise the hydraulic roughness of any given rough
surface, from the hydraulically smooth to the fully rough regime. The
method circumvents the unfavourable computational cost associated with
simulating high-Reynolds-number flows by employing minimal-span channels
(Jimenez & Moin 1991). Proof-of-concept simulations demonstrate that
flows in minimal-span channels are sufficient for capturing the downward
velocity shift, that is, the Hama roughness function, predicted by flows
in full-span channels. We consider two sets of simulations, first with
modelled roughness imposed by body forces, and second with explicit
roughness described by conforming grids. Owing to the minimal cost, we
are able to conduct DNSs with increasing roughness Reynolds numbers
while maintaining a fixed blockage ratio, as is typical in full-scale
applications. The present method promises a practical, fast and accurate
tool for characterising hydraulic resistance directly from topographical
scans of rough surfaces.
For more information, please contact Esteban Hufstedler by email at [email protected].
Event Series
GALCIT Colloquium Series